The aim of the International Journal of Applied Electromagnetics and Mechanics is to contribute to intersciences coupling applied electromagnetics, mechanics and materials. The journal also intends to stimulate the further development of current technology in industry. The main subjects covered by the journal are:

- Physics and mechanics of electromagnetic materials and devices- Computational electromagnetic in materials and devices- Applications of electromagnetic fields and forces

Abstract: The design and analysis of a novel salient-pole surface-mounted permanent magnet synchronous machine (SSPMSM) are presented in this paper for wide-speed range applications. In this machine, iron teeth are placed in the d-axis on the surface of rotor core to increase armature inductance and enhance the effect of d-axis armature reaction. But torque ripple is also increased since the rotor teeth increase the saliency of the machine. So segmented Halbach magnetization is applied to reduce the electromagnetic torque ripple. In order to investigate the characteristics of SSPMSM, four finite element (FE) models with different rotor cores and magnetizations are built.…Flux-weakening/enhancing characteristics, no-load characteristics and load characteristics are obtained and compared. The results show that SSPMSM has better magnetic field adjustment ability than traditional surface-mounted permanent magnet synchronous machine (SPMSM).
Show more

Abstract: Due to their advantages of high efficiency, high power density, and strong fault-tolerance ability, fractional-slot concentrated-winding permanent-magnet (FSCW-PM) machines are of particular interest in the applications such as wind power generation and electric vehicles. However, FSCW-PM machines suffer from rich winding magnetomotive force (MMF) space harmonics by the armature reaction field, which may increase eddy current loss. In this paper, a new low harmonic FSCW-PM machine is designed, which can reduce some space harmonics of low order in the air-gap flux density. A new magnetic equivalent circuit (MEC) model is developed to analyze the designed PM machine, which offers less…computation time and more calculation accuracy. Finally, a prototype machine is built and the measured results verify the theoretical analysis and the developed MEC model.
Show more

Abstract: This paper proposes a numerical scheme for the fast calculation of an efficiency map in Permanent Magnet Synchronous Motors (PMSMs). The efficiency map is the main performance feature required to design traction motors for electric vehicles. To obtain the efficiency map, iron losses must be calculated across wide speed and current ranges. The iron losses can be estimated from magnetic flux waveforms, which require a huge amount of non-linear time-stepping finite element analysis (FEA) solutions. In this work, the flux waveform estimation scheme is proposed aiming to reduce the number of required FEA solutions. The proposed scheme removes the redundant…FEA calculation based on the fact that the time variation of the field at one position is matched with the space variation of the field at one time step in PMSMs. To verify the effectiveness of the proposed scheme, not only the flux waveform, but also the iron losses and efficiency map of a PMSM is calculated using both conventional and proposed approaches. The comparison results show that the computation time to build a single efficiency map can be reduced from 8.8 hour down to 1.1 hour within around 5% errors.
Show more

Abstract: The bearingless switched reluctance machine with wider rotor teeth (BSRMWR) can achieve decoupled control of suspension and torque in the starter/generator system. This article makes theoretical analysis and simulations of generation mode in 12/8 single-winding BSRMWR. First, the generation and suspension principles of single-winding bearingless switched reluctance generator (BSRGWR) are explained; Second, the levitation force model of BSRGWR is derived based on the Maxwell stress tensor method. Then a suspension control scheme is proposed to eliminate the coupling of levitation forces in X and Y directions. This article also discusses the reasons why the generation currents of one phase should…be controlled symmetrically. Finally, the calculation of different control variables are summarized in a flow chart. Then the open- and closed-loop controls of single-winding BSRGWR are also included to justify that the generator can work normally.
Show more

Abstract: This paper presents a mathematical modeling of a magneto-rheological (MR) brake to determine a relationship between input current and output torque for applying a variety of control applications. The proposed model is consisted of two sub-models: a mechanical sub-model, using Bingham plastic model for MR fluid and a magnetic circuit sub-model through a semi-empirical method to estimate the nonlinear hysteresis behavior of MR brake used. The first mechanical sub-model using Bingham plastic model describes the magnetic filed dependent fluid characteristics and the relationship between the torque and the dynamic yield stress caused by the applied field. The magnetic circuit makes…up the second sub-model with the relationship between the dynamic yield stress and the magnetic induction of MR fluid. Due to the ferromagnetic property of the material used to form the flux path, MR brake experienced hysteresis effects and thus its hysteresis behavior is approximated through a semi-empirical method. The final model of MR brake links both sub-models together by the torque. An experimental setup is manufactured to evaluate the proposed model with a commercial MR brake used. The experimental result is compared with these predicted from the proposed nonlinear model in order to validate the model accuracy. The result shows that proposed model is reasonably predicted the hysteresis behaviors of MR brake. Moreover, the frequency response test of MR brake is carried out to evaluate the feasibility for a torque estimator in control use, and shows that the predicted frequency response matches up to the experimental characteristics and MR brake used has a bandwidth of nearly 35 Hz enough high to control.
Show more

Abstract: In this paper, a novel permanent magnet-assisted synchronous reluctance machine (PMASynRM) with rare-earth PMs and ferrite magnets is proposed. The performance of PMASynRM is discussed with respected to the different magnet ratio of rare-earth PMs and ferrite magnets. Some characteristics including the flux density, output torque, cogging torque, output power, power factor, torque ripple, loss, efficiency, and demagnetization are calculated by 2-D finite element analysis (FEA). The analysis results show that the excellent performance can be obtained by using hybrid magnet of rare-earth PMs and ferrite magnets with the suitable magnet ratio, and provide some desirable cost-performance trade-off.

Abstract: The core loss is of great significance in the machine designing and optimization. In the paper, an analytical method for calculating the flux density of surface-mounted permanent magnet synchronous machine is first presented based on the equivalent magnetic circuit and conformal mapping method. The model takes into account the slotting effect and stator saturation. Subsequently, the core loss was calculated by improved Bertotti’s formula in terms of the analytical model of flux density. Finally, experiment and finite element analysis (FEA) are used to validate the accuracy of the proposed analytical method for core loss. It shows that the analytical results…for core loss can keep excellent agreement with the experimental results and FEA results. Therefore, the analytical model provides a great potential to the machine designing and optimization.
Show more

Abstract: In order to investigate the impacts of the non-uniform temperature on the electric field distribution under PR (polarity reversal) voltage, the core loss and windings loss of a ± 500 kV converter transformer are calculated based on the electromagnetic theory firstly. Then the 2D fluid-thermal model of the converter transformer is adopted, and the temperature distribution under normal condition is obtained by utilizing the CFD software of Fluent. Afterward, the thermal data obtained from the mesh for computation of fluid-thermal field is mapped to the mesh for computation of electric field based on interpolation, and finally the…transient electric field distributions under different PR voltages are computed by the time stepping finite element method. The comparisons of the electric field distributions under different PR voltages at uniform and non-uniform temperature are conducted, which provides a reference for insulation design and fault analysis of the converter transformer.
Show more

Abstract: To obtain a large output torque and a long lifetime, a mesh-type harmonic piezoelectric motor is proposed in this paper. In addition, the operating principle of the motor is illustrated, and the displacements and forces of amplification mechanism are provided. Moreover, the equations of forces on the transmission system and output torque for the motor are deduced. By utilizing these equations, the output torque of the motor was analyzed and the influence of the system parameters on the output torque was investigated. Furthermore, the experiments of the displacements for the amplification mechanism and the output torque for the motor were…studied. The results showed that the largest test output torque is 0.383 Nm when the driving voltage is 150 V. The following parameters should be selected to increase the output torque of the motor: large offset a , length l 1 and l 5 , strain constant d 33 , elastic modulus of piezoelectric actuator c 33 , sectional width A p , small parameter b , lengths l 3 and l 8 and ceramic thickness l p . The results are useful for improving the performance of the motor.
Show more

Abstract: In this paper, power losses in high-speed switched reluctance machine (HS-SRM) is studied considering the copper loss, including skin and proximity effect, iron loss in machine side; switching and conduction losses in the drive circuit side using interactive coupled simulation methods. In high frequency fed electric machines, copper losses are increased due to the skin and proximity effects. Moreover, iron losses play a significant role in total electrical losses. Nevertheless, its computation is not straight. In addition, power electronics switching devices cause both conduction and switching losses in the SRM drive circuit. Switching loss may reach excessive levels with the…high-frequency switching. In this study, the losses are calculated detailed though coupled simulation method. Different wire constructions in the bundle are analyzed and compared. Finally, circuit simulation is performed on different switching devices. The results prove that high-speed switched reluctance machine driving and operating efficiency is really sensible to design methodology with suitable material and device selection.
Show more